How often should perimeter drains be cleaned?

February 23, 2009

Q: The time has come for us to convert our basement into a suite. The problem we have noticed when examining the concrete foundation a little closer is that there is water in one corner of the basement.

Our home is about 20 years old and I know we have perimeter drains as well as a sump pump. A neighbour has suggested that's the cause for the leaking. I must confess we have never had the perimeter drains cleaned out and many of our neighbours do this, regardless of any signs of leaking. Do you agree that this is something required on a regular basis?

-- Davin, Coquitlam

A: Over the years your clay, grey concrete or plastic perimeter drains will tend to silt up from the continued water hydraulics within the ground.

This can also be caused by tree roots, leaves from the roof, or shrubs planted close to foundation. Perimeter drains should be cleaned in older homes -- right away in your case, as you mentioned never having done this in the past.

You should repeat this every three years from this point on.

If it were a newer home, I would suggest having it inspected at five years and every year after that. By doing this, it will ensure that your drains will run unobstructed to the sump or storm sewer, reducing the hydraulic gravity pressure that causes the water to seep into the basement.

Before renovating, make sure you have this investigated further to avoid costly damage to your new renovation.